YY1 and infection: We found that YY1 knock out in either total B cells (Fig 6G) or naïve B cells (Fig 6H) significantly reduced EBV-induced proliferation early during infection compared to the CD46 knock out control and failed to generate YY1 knock out LCLs, however this effect was not EBV-specific as outgrowth of CpG-stimulated B cells was also reduced by YY1 loss (S7A Fig).